A 71 year-old man was admitted to the cardiology ward with a one week history of dizziness.  The ECG below was recorded on the second day of his hospital admission:

• Sinus rhythm with sinus arrhythmia, 75/min; Ventricular rate 39/min
• Second Degree AV block – both 2:1 AV Block and Mobitz I (3:2) AV Conduction

Comment: Note that conducted P-waves are conducted with a long PR interval (approximately 600ms)